I was thinking about building a standalone solar panel based Li-ion battery charger station, but I don’t know enough about electronics to do it. I would like to build it outside so that people can just bring their rechargeable flashlight batteries there to charge them.
So, I was wondering if I could take a couple of solar panels to charge, let’s say a motorcycle battery, or even a car battery for storing electricity.
Then from the car/motorcycle battery, I want to connect it to a Nitecore i4 v2 charger, or a Fenix ARE-C2 charger.
Sounds simple, right? But I don’t know what components to get and how to design the circuitry, if there are any.
First, I don’t know what volts or amps rated solar panel to get.
What I don’t understand is why the solar panel doesn’t burn up if you connect an auto / motorcycle battery to it. I’m thinking there must be a diode or some kind of circuit that allows the electricity to charge the battery, but prevents the battery from burning up the solar panels. Also, how does one prevent the solar panels from overcharging the battery?
Second, when I look at the Li-ion chargers, they have a 12VDC input so you can connect, for example a cigarette lighter adapter to it and charge your Li-ion batteries in your car. However, when I look at the electrical requirements, for example the Nitecore i4 v2 charger, it says it requires 12vdc @ 2amps. This is all fine and dandy, but what prevents the charger from getting more than 2 amps? Is there a circuit that controls the voltage and current?
Here is what I figured out so far.
The solar panels has to put out more than 12 vdc to charge the battery. A fully charged battery puts out about 12.7vdc. So to charge a car battery you can use up to 16 or 17 vdc. But how many amps does the solar panel have to put out? Rather than trying to figure this all out, I think I would rather buy a charge controller. What kind of charge controller would I need?
So then after that, how does one regulate the power to the electrical devices?